This application relates to deicer compositions with a reduced environmental impact. More particularly, the application relates to deicer compositions with reduced corrosiveness and biochemical oxygen demand that can be used as a liquid deicer, a pre-wetting agent when mixed with a deicing salt to form a pre-wetted deicer, or an anti-icer.
There is an ever present challenge to develop deicer formulations which are more effective and at the same time have a reduced impact on both the natural environment and infrastructure. In particular, there is a strong desire to find deicer compositions that have reduced biochemical oxygen demand (BOD) on water systems. Varieties of additives for deicers are currently used but have limitations. For instance, inorganic compounds such as phosphate and chromate based corrosion inhibitors are used. However, these compounds have undesirable environmental impact. Hexavalent chromium compounds are genotoxic carcinogens. Phosphates can contribute to eutrophication of lakes and streams. Others have developed deciers that have used organic compounds as additives. Examples include desugared beet molasses (U.S. Pat. No. 7,473,379), honey (U.S. Pat. No. 6,616,739), low molecular weight carbohydrates (U.S. Pat. No. 6,299,793), and molasses (U.S. Pat. No. 6,596,188). However, organic additives are not without their own potential for detrimental environmental impact. In particular, the types of organic additives commonly used in deicers are usually readily biodegradable, resulting in the potential for increased biochemical oxygen demand (BOD) when these additives get into natural waters. Increased BOD can impair the living ecosystem in natural waters, resulting in death of fish and other aquatic organisms if BOD is sufficiently high. Thus, it is desirable to identify additive systems for deicers that have reduced BOD.
Deicer compositions can include a liquid deicing agent combined with at least one corrosion inhibiting additive and at least one viscosifying additive. The deicing composition can be used in a variety of ways, including alone as an anti-icer or deicer, or as a pre-wetting agent to combine with a solid deicing agent to form a pre-wetted deicer. When used as anti-icers they are applied directly to a surface prior to a snow storm or ice event. They serve to interrupt the boundary layer of snow between the surface and the accumulated snow pack, thereby preventing the snow from bonding to the surface and facilitating its removal by snow plows. The deicer composition can also be used as a deicer to melt snow or ice that has already accumulated on a surface. The deicer composition can also be used as a pre-wetting agent having a liquid deicing agent either alone or with additives that are added to or blended with a solid deicing agent to yield a pre-wetted deicer. The solid deicing agent can include compounds such as urea or a sodium, potassium, magnesium, calcium or ammonium salt of chloride, carbonate, lactate, succinate, acetate, propionate, formate, or combinations thereof. Examples include, but are not limited to, sodium chloride, magnesium chloride, calcium chloride, potassium chloride, potassium carbonate, urea, sodium acetate, potassium acetate, ammonium acetate, calcium magnesium acetate, sodium formate, potassium formate, potassium lactate, sodium lactate, sodium succinate, potassium succinate or combinations thereof. The pre-wetting agent can be sprayed onto the solid deicing agent or preferably it is pre-blended with the solid deicing agent. This allows those applying the deicer compositions to the road to use the same standard equipment and trucks that used when applying dry salts to the road.
The present invention allows for a reduced environmental impact while still providing an effective deicer composition. Surprisingly, it has been found that certain combinations of additives can provide effective corrosion inhibition at reduced BOD levels, such as when utilizing a corrosion inhibiting additive such as gluconate with a viscosifying additive such as xanthan gum in chloride deicers, which provides corrosion protection at even lower BOD levels than is possible with either additive by itself or compared to other additives.